What are public private and protected in object oriented programming

Question

What are public  private and protected in object oriented programming

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They aren t really concepts but rather specific keywords that tend to occur  with slightly different semantics  in popular languages like C   and Java    Essentially  they are meant to allow a class to restrict access to members  fields or functions   The idea is that the less one type is allowed to access in another type  the less dependency can be created  This allows the accessed object to be changed more easily without affecting objects that refer to it   Broadly speaking  public means everyone is allowed to access  private means that only members of the same class are allowed to access  and protected means that members of subclasses are also allowed  However  each language adds its own things to this  For example  C   allows you to inherit non-publicly  In Java  there is also a default  package  access level  and there are rules about internal classes  etc

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They are access modifiers and help us implement Encapsulation  or information hiding   They tell the compiler which other classes should have access to the field or method being defined    private - Only the current class will have access to the field or method   protected - Only the current class and subclasses  and sometimes also same-package classes  of this class will have access to the field or method   public - Any class can refer to the field or call the method   This assumes these keywords are used as part of a field or method declaration within a class definition

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To sum it up in object oriented programming  everything is modeled into classes and objects  Classes contain properties and methods  Public  private and protected keywords are used to specify access to these members properties and methods  of a class from other classes or other  dlls or even other applications

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as above  but qualitatively  private - least access  best encapsulation protected - some access  moderate encapsulation public - full access  no encapsulation  the less access you provide the fewer implementation details leak out of your objects  less of this sort of leakage means more flexibility  aka  quot looser coupling quot   in terms of changing how an object is implemented without breaking clients of the object  this is a truly fundamental thing to understand

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A public item is one that is accessible from any other class   You just have to know what object it is and you can use a dot operator to access it   Protected means that a class and its subclasses have access to the variable  but not any other classes  they need to use a getter setter to do anything with the variable   A private means that only that class has direct access to the variable  everything else needs a method function to access or change that data   Hope this helps

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All the three are access modifiers and keywords which are used in a class  Anything declared in public can be used by any object within the class or outside the class variables in private can only be used by the objects within the class and could not be changed through direct access as it can change through functions like friend function  Anything defined under protected section can be used by the class and their just derived class

[class] What are public, private and protected in object oriented programming?

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